Electrical cable of the type known as "interlocked armor cable" is widely used in power distribution systems in commercial and industrial applications. This type of cable consists of one or more insulated electrical conductors encased in a protective interlocked armor. The interlocked armor is made from a strip of metallic material, usually galvanized steel, helically wound around the conductors and interlocked upon itself to form a flexible tubular protective covering for the conductors. In some applications the interlocked armor cable includes an outer coating or jacket of vinyl.
At the terminations of the electrical cables where connections are made to the electrical conductors, it is generally necessary to ground the metallic interlocked cable armor by securing a grounding conductor to the cable armor. This has been conventionally done in various ways. For example, where a large number of cables terminate at a common location, one widely used means for grounding the cable armor involves using a clamp similar to a radiator hose clamp and a grounding lead. The clamp is positioned over the end of the cable armor and the grounding lead is positioned between the clamp and the cable armor. The clamp is then tightened to secure the grounding lead to the cable armor. The grounding lead may then be secured to a suitable grounding conductor. It should be apparent that this practice has several disadvantages and limitations. The need for several separate parts in order to effect a single connection is cumbersome for the workman and is relatively expensive. The presence of a clamp at the end of each cable causes a protrusion on each cable which makes it difficult to group the cables in a compact neat arrangement. Additionally, this practice is relatively time consuming and difficult to accomplish when working in narrow or confined areas.
Where single cables terminate at a junction box or electrical panel, special terminating fittings are generally employed. One well known type of terminating fitting, often referred to as a "PLM" fitting, is made of cast metal and incorporates a set screw type arrangement for securing the fitting to the interlocked cable armor and threaded bushings or nuts for securing the terminating fitting to the panel. Terminating fittings of this type are relatively expensive and time consuming to install, usually requiring tools such as screwdrivers and/or wrenches for installation.
With the foregoing in mind, it is an important object of the present invention to provide a connector which is particularly designed for use with interlocked armor cable for facilitating connecting a grounding conductor to the cable armor, and which is considerably more economical and easier to use and install than the presently available connectors or clamps for use with interlocked cable armor.
it is another object of this invention to provide a connector of the type described which is particularly suited for use where a relatively large number of interlocked armor cables terminate at a common location, and which permits the cables to be grouped in a more compact and neat arrangement than with the practices presently available.
It is still another object of this invention to provide a connector of the type described which is also useful for securing a single interlocked armor cable to a junction box or panel while also facilitating connecting a grounding conductor to the cable armor.